A generic valve control device is disclosed in publication DE 199 03 594 A1. In the valve control device illustrated in this publication the fluid is applied to both sides of the second rotor in the form of an impeller rotor with fluid pressure chambers, so that the lock bolt may be removed from the lock opening and released free of subjection to transverse forces, independently of the particular fluid pressure chamber which is pressurized at any given time. Inherent in this valve control device, however, is the disadvantage that repeated insertion into the lock opening and locking of the lock bolt cannot be ensured. When the internal combustion engine is shut off residual torque acts on the camshaft, so that the fluid pressure cannot drop on the side supporting the impeller rotor. As a result of leaks the impeller rotor is then rotated from its locking position, so that the lock bolt may not be inserted into the lock opening and effect locking.
Also of the state of the art is application to the lock bolt of fluid or oil from only one side of the first rotor in the form of an impeller rotor, so that the locking conditions for the lock bolt are always clearly indicated. The problem arises here, however, that the lock bolt may be removed from the lock opening and effect locking only if sufficient pressure has been built up on the respective side. But this has the result that the lock bolt may not be removed from the lock opening and effect release free of subjection to transverse forces; in the event of delayed release this may lead to a tendency to jam and to high wear of the locking system.
On the basis of this state of the art the object of the present invention is to provide an improved adjustable valve control device which makes certain that the lock bolt is locked and unlocked at the proper time, that is, that it is fully inserted and locked when the internal combustion engine is started and later unlocked when the oil pressure has been fully built up in the cylinder head, independently of the pressure relationships in the fluid pressure chamber.